Biodynamic response of the seated human body to single-axis and dual-axis vibration: effect of backrest and non-linearity
Biodynamic response of the seated human body to single-axis and dual-axis vibration: effect of backrest and non-linearity
The biodynamic responses to the human body give an understanding of why human responses to vibration (changes in health, comfort, and performance) vary with the frequency and direction of vibration. Studies have shown that biodynamic responses also vary with the magnitude of vibration and that the backrests of seats influence the transmission of vibration to the seated human body. There has been little study of the nonlinearity in the biodynamic responses of the body to dual-axis excitation and no study of the influence of backrests during dual-axis excitation. This study investigated the apparent mass and cross-axis apparent mass of the human body exposed to random vibration (0.2 to 20 Hz) in all 15 possible combinations of four magnitudes (0, 0.25, 0.5 and 1.0 ms(-2) r.m.s.) of fore-and-aft vibration and the same four magnitudes of vertical vibration. Nonlinearity was evident, with the body softening with increasing magnitude of vibration when using a fixed magnitude of vibration in one direction and varying the magnitude of vibration in the other direction. The fore-and-aft apparent mass on the seat was greater without a backrest at the lower frequencies but greater with a backrest at the higher frequencies. The vertical apparent mass on the seat was decreased by the backrest at low frequencies. Cross-axis coupling was evident, with excitation in one axis producing a response in the other axis. It is concluded that the nonlinearity of the body evident during single-axis and multi-axis vibration, and the influence of backrests, should be taken into account when determining frequency weightings for predicting human responses to vibration and when optimising the dynamics of seating to minimise exposure to vibration.
37-51
Qiu, Y.
ef9eae54-bdf3-4084-816a-0ecbf6a0e9da
Griffin, M.J.
24112494-9774-40cb-91b7-5b4afe3c41b8
11 February 2012
Qiu, Y.
ef9eae54-bdf3-4084-816a-0ecbf6a0e9da
Griffin, M.J.
24112494-9774-40cb-91b7-5b4afe3c41b8
Qiu, Y. and Griffin, M.J.
(2012)
Biodynamic response of the seated human body to single-axis and dual-axis vibration: effect of backrest and non-linearity.
Industrial Health, 50 (1), .
(doi:10.2486/indhealth.MS1298).
(PMID:22146145)
Abstract
The biodynamic responses to the human body give an understanding of why human responses to vibration (changes in health, comfort, and performance) vary with the frequency and direction of vibration. Studies have shown that biodynamic responses also vary with the magnitude of vibration and that the backrests of seats influence the transmission of vibration to the seated human body. There has been little study of the nonlinearity in the biodynamic responses of the body to dual-axis excitation and no study of the influence of backrests during dual-axis excitation. This study investigated the apparent mass and cross-axis apparent mass of the human body exposed to random vibration (0.2 to 20 Hz) in all 15 possible combinations of four magnitudes (0, 0.25, 0.5 and 1.0 ms(-2) r.m.s.) of fore-and-aft vibration and the same four magnitudes of vertical vibration. Nonlinearity was evident, with the body softening with increasing magnitude of vibration when using a fixed magnitude of vibration in one direction and varying the magnitude of vibration in the other direction. The fore-and-aft apparent mass on the seat was greater without a backrest at the lower frequencies but greater with a backrest at the higher frequencies. The vertical apparent mass on the seat was decreased by the backrest at low frequencies. Cross-axis coupling was evident, with excitation in one axis producing a response in the other axis. It is concluded that the nonlinearity of the body evident during single-axis and multi-axis vibration, and the influence of backrests, should be taken into account when determining frequency weightings for predicting human responses to vibration and when optimising the dynamics of seating to minimise exposure to vibration.
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e-pub ahead of print date: 6 December 2011
Published date: 11 February 2012
Organisations:
Human Sciences Group
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Local EPrints ID: 186579
URI: http://eprints.soton.ac.uk/id/eprint/186579
ISSN: 0019-8366
PURE UUID: dae26e2b-777f-44c1-822f-847fb3df9f01
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Date deposited: 13 May 2011 13:16
Last modified: 14 Mar 2024 03:20
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M.J. Griffin
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